Piston and piston ring combination



Aug. 26, 1952 c. w. HoLLlNGswoRTl-l 2,608,452 PISTON AND PISTON RING COMBINATION Filed sept. 4, 1948 l Il llI 22 Z0 l 9 3 `Patented Aug. 26, 1952 UNITED STATES PATENT N OFFICE Carl W. Hollingsworth, Marshalltown, Iowafassignor` of one-halfl to Thomas J. Kemp, Lincoln,

Application September 4, 1948, Serial No. 47,870

JThis invention relates `to a piston and piston ring ofa certainV construction and relation to eachother. NThe production of Aa, satisfactory piston and piston ring haslong been` a'lmajor problem, and most, `ii not all, of the constructions in use today are unsatisfactoryinalnumber of particulars. l

Itis true there are manyfobstaclesto overcome, and the solution of the problem is notsimpleQQV It is most desirous that the rings have sutil-l ciently tight `bearing engagement with thejcylinder wall `and ring grooveto Vattain maximum compression in` the combustion chamber; the rings must also be'effective to retain-,the lubricating oil in `the crank case and prevent ity `from entering into the combustion-.chamber except in the very small amount necessary t'lubricate th top of the cylinder wall. FOne of the specific difficulties is'that the passage ,of combustion` mixture or lubricating oil does not occur only between the rings and cylinder, but it also occurs between the `rings and grooves, i` e., through the grooves around the rings. It is usually possible to prevent passage between the rings and cylinder wall, but the problem cannot be solved simply by preventing such passage. The lubricating oil collects on the cylinder wall in the form of a film each time thel piston moves to the top of` the cylinder; when the piston de scends, the rings should wipe or scrape oi the film of4 oil in excess of the small amount necessary for proper lubrication.

The piston reaches a high rate of'speed in its movement Vin the cylinder, and when a ring encountersthe oil at such a speed, theoil takes on the characteristics of a solid. Thus, when the ring `encounters the oil at a high rate of speed, thewexcess oil is not readily wiped or'scraped off the cylinder wall, and responds similarly to a solid material, such as metal. As a result, the oil piles up ahead of the ring.

The ringhas difficulty in moving Athe oil along, and something must give way. The ring may then be compressed inwardly which causes the ring to pass over part of the oil on the Wall of the cylinder, instead of removing the excess oil. The action may be compared with a scraper or squeegee.A 4If a squeegee is employed to `wipe a liquid from a surface, and the squeegee is moved swiftly, the reaction force of the liquid actually lifts the squeegee oi the surface, allowing some of the liquid to remain spread on the surface.l

If the ring is of suiiicient strength to maintain tight engagement with the cylinder wall in spite 19' claims. (o1. aos-7) l of all obstacles, the oil piling fup ahead of thering enters into the groove andiinds its way in that manner around the ring.l ABoth probably occur simultaneously. l l I l `All of the oil thatpasses-by the ring, does not do so by mere inertia of the oil when encountered by the rings, on the intake stroke of the piston,a partial vacuum is `created in `the combustion `chamber and this condition tends to actually draw the oil pastA the ring into `the combustion chamber. f j L Where two `compression Vringsonlyare used,

and one -or two conventional `oilrings are ,alsoused, a portion of the` combustion gases pass 4by the rings and blow some of the excess `oil* d own into thecrank case. M'Ihis actionreduces oil conf sumptionfbut dilutes the oil,` and also causesloss` of p ower. As `the rings wear in,` making a tighter seal theyseem to act lile valvesLcausingvthe oil to be pumped into thecombustion chamber. This change that takes place often'makes, thev motor workfmore powerfully' on account oi the better seal for both intake and power stroke but oil consumption goes up. I feel that excessoil` must be removed: before it comes-in contact with any; thing but the bottom compression ring. In order toprovide mosteiectivelyfunremoving the excess oil from`thegcylinder walLI provide a deiiectoredge on thejunder surface of the bottom compression ring,` which acts as a plane bit in removing the foil.` The deflector edge is curved sor that the oil readilytravels thereover; and I provide a groove `in the piston for the oil to pass into, the' groove beingopen to the interior of the piston at substantially all points around the piston. Thus the excess oil is removed before it comesin Contact with the upper compression rings.V j The piston and ring constructionof the present invention overcomes theA disadvantages referred to above. `My invention takes into account three very elemental but lexceedingly important considerationsf (a) a material is to be moved, (b) a place is providedl for the material to be moved to, and (c) means isprovided for moving the material'to. the place desired. i An object of thepresent invention is therefore the provision of a novel piston ring which removes the excess lubricating oil from the `cylinder wall in such ajmanner that the characteristics of a solid, as above referred tmoer the least resistance to the oil being removed. .l

Another object is the'provision of a 4piston and piston ring comprising a novel construction wherein ample space is provided through which to move the oil after it is removed from the cylinder wall.

A further object of the invention, and a result of the next previous two features, is the provision of a novel piston and piston ring wherein the oil to be removed from the cylinder wall is prevented from being passed over by the ring, either next to the cylinder` wall vor through the ring groove,

A still'further object is the provision of a piston and piston ring in the use of which blow-by is almost completely eliminated.

Another object is the provision ofa piston and piston ring in the use of which anf'oil ring, Yas it is usually known, is unnecessary;V 1

Many previous ftypes of piston and ring 'con-`v structions employed openings in the ring grooves in an eifort to overcome the vobjections .set out above; I am convinced that such a step does not overcome the objections. the lubricating oil and combustion mixture passes relatively through thering groove and around the ring, and if an opening is provided in the ring groove the passage of the oil through the groove is made more easily.

A still further object of the invention is the provision of a piston and pistonring which accomplishes the above mentioned desired results, without having openings in the ring grooves.

Still another object of the invention is the provision of a piston and piston ring having novel features. of construction for carrying out the above objects, which can be made by economical methods, i. e., by the elimination of milling and` drilling.

With these and other objects in view, my invention consists in the construction, arrangement and combination of the various part-s of my device whereby the objects contemplated. are attained, as hereinafter more fully set forth, `point-k ed out in my claims and illustrated in the accompanying drawings, wherein:

Figure 1 is an elevational view of a piston made according to the present invention showing piston rings therein;

Figure 2 is a vertical sectional -vieW taken on line 2-2 of Figure 1, but with the piston rings omitted; Y

Figure 3 is a horizontal sectionalview taken on line 3-3 of Figure 2;

Figure 4 is a greatly enlarged sectional view y.

taken on line 4 4 of Figure 1;

Figure 5 is a view similar to Figure 4, showing the piston ring in raised position;l

Figure 6 is a greatly enlarged view of that portion enclosed in dot-dash lines in Figure 4; Figure 7 is a view similar to Figure 4 showing a slightly different form of piston construction; Figure 8 is a view similar to Figure 4 showing an alternate form of groove in the piston ring;

Figure 9 is a view similar to Figure 4 showing.

another form of piston ring andgroove in the..

piston ring;

Figure 10 illustrates a piston ring having a modified form of peripheral surface;` f Figure ll illustrates a tapered piston ring; ,and Figure l2 is a detail similar to Figure 4 showing the relation of one of the struts holding the parts of the piston together and the groove in the piston. j

l lteferring now in detail to the drawings, Figure 1 illustrates a piston as a whole at I2. For convenience, the upper part of the piston is indicated at I4 andthe lower part at I 6, and a cylinder wall is indicated at I8. The upper portion I4 of the piston hase plurality of ring grooves 20 which surface, 30.

For example, :much of 4 may be conventional in form, and therefore conventional piston rings 22 are employed.

Below the conventional piston ring grooves 2Q is another ring groove 24 of special construction and forming a part of the present invention. The groove 24 is shown as of greater vertical extent than the grooves 20, but, as the description will later reveal, the vertical heightV of the groove 24 is vnot critical. It will beunderstood that certain proportions and relationships are exaggerated for the purpose of clarity and specific relationships will be significant only as specifically referred to.

' The.-lower ring groove 24 (Figs. 4 and 5), includes an upper vsurface 26, a vertical surface 23 forming the floor of the groove, and a bottom yThe bottom surface 3B terminates radially outwardly at the point 32 (Figure 6) and it will be noted that this radially outer edge of the bottom surface 30 is disposed inwardly of the main portion ofthe piston. A space 34 (Figs 4 and 5) Ais ,indicated between the upper portion of the piston and the cylinder wall. This spacef is greatly exaggerated, and it will be understood that thisY space is normally not detectable by the eye, but there is, nevertheless, an. appreciable space when considered in micrometer measurements. Another space 36 is indicated between the lower po-rtion I6 and thev cylinder wall-tand, this space is less than the space 34 as is well understood by those familiar with the usual con.

struction of pistons. The point L32 therefore terminates radially outwardly at a point disposed inwardly from the outer surface of the pistony with respect to both the upper and lower portions of the piston and consequently at a considerables space from the cylinder wall.

Immediately below the ring groove 24 is a. peripheral groove 38 which ,entirelysurrounds t e piston and` extends downwardly and inwardly.,

factithe two surfaces mentionedabove. do con-v verge. Y

The peripheral groove 33 ydenes the demai-cae.V

tion line betweenthe upper and lower portions of the piston, and means is of course provided to secure the two portions together. In the mold for casting the piston, lugs or struts 43 are formed integral with the portions of the pistons.V In the molding or casting process, wrist pin bearings 42 are formed and extending upwardly from the. bearings 42 are additional Vstruts 44 inter-connec--- ted by Aa web 4t. The struts 44 and web 46 form, additional means for securing the two portions.: of the piston together, and while they are of.' greater width than the strutsll, they do not detract appreciably from the general open and continuous feature of the groove 38. For practical purposes, the groove 3S is continuous around the piston, having communication with the interior of the piston at substantially allpoints. therearound.m

The vring grooves 2Q and 24 and the peripheralgroove 38 can all be formed by. a .lathe operation andit is pertinent to point out here that in the formation of the piston, expensive milling procV` esses are eliminated,A thus making for more economical manufacturing.

5.,; l A piston ringf48 isplaoed in the groove .24." The cross-sectional contour of the ring v48 ispreferably rectangular, similar-to conventional rings However, the ring 48 is providedwwitha circum ferential groove 50 (Figs. 4, 5 and 6) cut in the under surface of the ringl adjacent its outer peripheral edge. Reference-Fis directed to; Figure 6 showing the groove yll'in enlarged detail.` `The outer marginal edge of thelgroove 50findiated at 52 is Acloselyadjacent vthe outer peripheral surface of. the ring. yThe numeral 54 indicates v`the radially inner portion ofthe groove 50 and par,` ticular .attentionis directed tothis portion 54. The" portion 54 terminates in lthe plane ofthe under'srface of the'ring .atV a point disposed radiallyl outwardly beyond .the outer edge of the bottom surface 30 of theringl grooveor thelpoit 32.1 Thus, th'e downward extensionof portion 54 as indicated' by the dot-dashfline'56'is disposed radiallyA outwardlybeyondthe point 32 or beyond the l outer 'edge' of r the bottornsiirface off the 'i Comparisonof Figures 4"an'd`5'wil1 show that the ring has 'limited'.vertical': movement ir'fthe ring groove. On the up: stroke of" the piston,` the ringbears against Athe bottomsur'faceBD'as shown in Figure4, 'and on zthedown strokethe ring bears against the upper 'surface Millas` shown in Figure 5: There is also` a space .betweenl the `inner surfaceofjthe ring'iandt theffloor2'8"of the ring groove:V These spaces ardor course, exaggerated in thexillus'trations: 2 Thecurvature of the Agroove 50T in 'cross-section' issuch that regardless L'of the vertical position of the` ring in 'the groove the projectionof the -surface '54 as` indicated by the i liney'BtL` is always' disposed radially' foutwardly be-4 yond the point 32. i

."Duezto the shape and "dispositionioff the groove 38, 'ftlief outer'"marginal"edgey 'thereof '58 (the counter par't 'of `the point 32) is dispose'd below the bottom" surface A3l] ofthe ring groov'ei"1v .'Ho'wever; I" also contemplate forming the pe; riplieral'groove. in' the shape indicated fat? 60 in' Figure 7. `In this-instance,` the size and inclination'of:- the groove' is 4such that the outerpoint 62 'which `corresponds with th'epoint -58 terminate'ssubstantially in theplane offthebottom' surface 30 of the ring groove. `In other respects,` the'I embodiment illustrated in Figure 7 is' similari to'that-in Figures 4 'and"'5, and it will be unde'ri i FigureSillustrate's a groove-64. c'u't inthe ring so that the inner marginal edgeof' thgrooveisl circumferential"projection 158i4 forrnedw-on` `the under surface Iof 'the ring land disposedradially` outwardly beyond -thecuter edge of the bottom..4

surface 30 and, offfcourse, the main portionofV the ring is" adapted to bear` against ilhesuri'acerBO.` withtheprojection `68 extending therebelow-q Formed` in the under` surface of the projection E8 `is a circumferential groove 10, and'in this-in 9 illustrates a siighny different-kind of: piston ring. The piston ring is providedfwithfal Vmoved to; i. `-c.` `A means is provided for'moving the i'haterial` stance also the downward projection of theinner edge oifthe groove is disposed outwardly beyond the radially outer edge of .the bottom surfac'eili:

of the ring groove. `The form of rin'gfillus'trated in Figure 9 can be employedwith pistonsshavingi peripheral grooves .either of theform indicatedl at 68 orithatindicatedat 38. J 2

Figurelo shows a piston lrng-48 formed' by a cutaway' portion-thereabovei.,

t Figure 11 Vmustrates a ring `4s navragen-tapered f surface'14. 2

i The rings of Figures .10 and 1l can beiused anyof the piston constructions showns In Seither.,

of these two `forms, of ring, there is a reduced surface which bears on thev cylinder' wa1l.|8and" as:`

a` consequence; increased vpressure isr exerted* on the cylinder wall in that area 'wherefthe ring: The (greater pressureaexerted f engageskthe wall. insures thata minimum,` if any excess oil passesbetween the ring and cylinder' wall, andi with the@ otheradvantages enumerated above, suchas: the groove 50 directing theoilinto the groove 38,'4a

most effective piston' and kring` construction? isi accomplished, in whichfrninimum oilmriecessary for'top cylinder lubrication passes into" the'com'e" bustion space. 1 i,

In connection with the rings of Figure theYV increased pressure brought about bythe lre'duc'ed.

area of the projection12 assuresapefectfseal against the passage offexcess oil; theldifferencew in diameter between the projection and' the l'c utf away portion'lneed be yonly a fewflthousandthsofi. an inch and when therprojection w'ears dowmthef `whole surfacebear'slon the' cylinder;nwalliibutf by that time the4 ringsfare seated by wear against f the cylinder.` wall, and thereis noneed for"A creased pressure in a localized Iarea; l Thusv there is a perfectseal initiallyand a 'continuing-iperfect seal as the ring Wears; ,Thus for controlling the oilat various speedsof thepiston-,fzdilferent widths "of the `surface engaging 'the'. cylnderfwall.

may be providedya' decrease -of widthgresultsin an increaseof pressureper unit area; andy makes more positive the oil.

f In any of the instances afb'oveyith'e.projection4 of the inner edge of :"thefgroovein:'thefirngffas:

indicated by the lines' 56 Tand'wrrieednot be parallel with theinner surface of the "peripheral I groove; the only "condition being: thatetheyare disposed outwardly beyond :the Louter fedge of the@ bottom surface 3D of the ringfgroove :l

Froxn theabove` detailed description,` ittw i l a. Azmaterial is to `bemoved; i i b. A place is` provided for thev material" to be to` the,place desired. y i

.'Alm of oil forms on the Acylinder..'.feacluix` time that `the, piston` movesupwardly. When".4

the piston 'movesfdownwardl it is of Vcourse Val=r4 Ways intended that the ring wipe orfscrape' the?q oil oiiof the cylinder wall andcarryit down'into..y thecrank case. .The piston moves at a consider-Ll!v ablefspeed and when'itencounters f'the iilmwoiiA oil the oil piles up ahead of the'ring andinlthe` down stroke the ring assumes the .position shown` in Figure 5. In the case of previously known:

typeszqf pistons and rings, the oil piling up ahead' of thering is; then forced Vinto. the; groove below...`

wanna` modif iled peripheral surface having a projection 512':

the deflection action? Fin s removing'.

lbe

evident that thel objects "of` the invention-'cani The effectively `accomplirshedr; As` statedfin the-tina4 troduction, there` are` three fundamental,H but iin-I portant, considerationslto be taken into `accountatdie'rlng:v andfollows its( course past the' ring through the'groove behind the ring. The present' invention: prevents such; a phenomenon. The circumferential groove, suchas 50, forms a relatively' sharpened outer edge. which engages. the cylinder wall and thissharp'ened edge-scrapes-the oil oil` of the cylinder Wall and deilects-it. They oil then follows around the groove in the. ring and is forced out of the groove in the directions'.

indicated by theprojection lines 56 or; 6G. Since the inner. edge of the groovein the rngis disposed outwardly beyond the bottom surface inV allpositions of the piston, the oil is effectively prevented from enteringinto the space betweenv the-ringe and the surface 30 and instead is de'-l ecteddownwardly into theperipheral groove 38.

The general open-work nature of the peripheral groove 38 enables oil to freelypassfinto the interior ofthe piston.; This'groove must preferablybe as nearly continuous'as possible,.brokenonly by the'struts which are necessary to hold'.

theportionsof the piston together Any -oi1 which strikes the struts .40 or theelements 44,

I6 is deflected circumferentially and permitted to pass through the open portion of' theigroove.4 Attention is directed to Figure 12 which shows,

one of the struts 40 and its relation to theperipheral vg-roove 38.- It will be noted that the bottom surface of theperipher'al groove 38 forms a relatively wide angle with the strut, with the y consequence that .thereis ample space in 1 the;

peripheral groove outwardly of the strutto`receive oil, whereby a great quantity ofoil can be received and then the oil ilows laterally off; ofV the strut into the interior of the piston. For.. all: practical purposes, inthe present case, the pe. ripheral groove 38.?(as well as B0). is open cone tinuously-'around the piston.

The ring' can be made toueng'age the cylinder wallfwith suilicient'pressure to` assureithat no; oil will pass lbetween the ring and the cylinder'l wall exceptthe thinnest film necessary for proper lubrication, and since no -oi1 pressure forces the oil' through the grooves aroundthe ringsga perfect excess oil return is accomplished. Also, it might be pointed out Ythat the tendency ofthe" vacuum created in the combustion space on the intake stroke will notpull the oil to excess into the combustion chamber because the excess oil has been kept from the'ring grooves and piston surface 30 of the ring'groove.

By comparison with certain previous and less satisfactorypiston andring constructions, it will` opening in the groove and the space betweenthe'- pis-ton, and cylinder wall. There is continuoussplashingof oil in the cranky case and as a consequence oil passesthrough theopening-in the ring groove and on through the groove into the space between the piston and cylinder w'all and then r into the combustion space. Conversely, on the power stroke, the gases of combustionnd their way through the same passages inthe reverse `walls by deflection into the peripheral groove 331.50

and is prevented from encountering the bottom` 8: direction: This is4 made more Yobvious when it is considered that `at the end of the compression stroke: the'ring is vdisposedin the bottom of thegroove'andbeforethe piston beginsv its power' stroke sothat the. ring would be at the top ofthe groove,.the gases-*of'cornbustion pass between the ring. and the uppersurface ofthe groove and. on

through the opening in the groove.l

In order to'carry out the above advantagesto a furtherv degree, Iprovide a groove I6-inthe. under surface of the piston. AS the piston de' scends,` the groove 16'is effective for wiping or: scraping oil a certain portion ofthe lm of oil. from the cylinder wall, and although. the ulti-` mate control is eifectedby the piston ring, theigroove 16 aids in that direction.

While I have herein shown and described mentof the parts withoutdeparture, from' the `spirit`andscopethereof; `I do not therefore wish to be understood as limiting my invention-to the.-

precise forms herein disclosed, except as Imay beso limited by the appended claims: v l

VI claim as rnv-invention:`

1. A piston and piston ring construction; comprising, al piston .having a ring-groove, a ring in-vv said'groove, `the bottom surface of said groove' terminating radially inwardly from the main surface of= the piston, said piston having a periphe eral groove `generally below said ring groove and communicating withv the interior of the piston,

said ring having a circumferential groove in itsunder surface, the radially inner edge of said circumferential groove being disposed outwardly'be yond the radially outer edge of the bottom sur face of said ring groove. i

' 2. Ina construction of the character described,

the combination comprising, a piston having a v ring groove, a ring in said groove, said rng'having a limited amount of. vertical movement in said groove in the normal operation of the piston,

the -bottorn surface of said groove terminating' radially inwardly from the main peripheral surface of the piston, said piston having a peripheral'groove generally below said ring grooveand communicating with the interior ofthe piston, said ring having a circumferential groove in its under surface, the portion of said'circumferem tial groove, as determined by its cross section, deiningy the. radially inner termination of the groovebeing so shaped that a line extending theV protection downwardly of said portion is disposed radlally outwardly of the outer edge of the lower surface of said ring groove in all vertical positions of said ring in said ring groove.

3. In a construction of the character described, the combination comprising, a piston having a ring groove, a ring inV said groove, said ring having a limited amount of vertical' movement in said groovein the normal operation of the piston, the bottom surface of said groove terminating radially inwardly from the main peripheral surface'- ofthe piston, said piston having a peripheral groove generally below said ring groove and communicating with the interior of the piston, said ring having a circumferential groove in its under surface, 'the radially inner and outer edges of said circumferential groove being disposed in theplane of the under surface of said ring,l the portion of said circumferential groove, as determined byits cross section, dening the radially inner termination of the groove, being so shapedV that aline extending the projection downwardly, of said portion is disposed radially outwardly of preferred vembodiments'of my invention, manifestly it is susceptible 'of modification and. re-arrange-l the outer .edge ofthe lower surface ofv said ring `groovein all vertical positions of said ring in said `ring groove. l i

4. A piston and piston ring construction, comprising,` a `piston having a ring groove, a ring in .said groovethebottom surface of said groove .terminating radially inwardly from the main surface of `the piston, said. piston` having aperipheral groove generally below said ring groove, said -peripheral groove,for all practical purposes, havingcommunicationwith the interior of the DiS- ton at all pointsaround the piston, said ring having a circumferential grooveinits under surface,

'Said circumferential groove being '.,dispQsledmi-,auy `radially outwardly of the,lowerfsurface'ofsaid .-Ingg groove. u

`5,. Ar piston and piston ringconstruction comandl communicating with the interior of the pisboa-seid ring having; a. circumferential l groove in/its under surfaceVthe radially inner `edge of said circumferentialgroove lying in the plane of .theunder surface of the ring .and being disposed .ouiwardlvfbevoe the radially-Outer ledge. of .the bottm swagger, said.: ring groeve. and: .the radiallyouter edge of Asaid circumferential groove lyingfin` the outer peripheral surface, of the, ring. 16. In aconstruction of the character, described,

combination comprising, `a ,piston `havinga ring-1groove,` allfinginV `said groove, the outer `edge .o ffthe. bottom ,surface lof,` said ,groove `being dis posed radially` inwardly 1of the ,mainsurface of .the eisten .Seid-Piston hevige anefieheal arcor@ generally eelavv,l saidf ring i empre. and communieating withthezinterior of theY piston at substaniiallvfell Vpeintsier =l1mireniiel1riof the pieten' the innenedge of said peripheralgroovebeing substantially,,coincident with` the outenedge of the bottom surface. of said ring groove.: said ring havinga circumferentialgroove in its under surface, the` radially. inner edge of said .circumferf I entialg'roove being `disposed"radially outwardfber yond the outer/edge' of ,thebottomsurfac'eI o'f said ring groove.

'7.` Ina construction of the-character described, the combination comprising, a piston having a ring groove, a ringin saidjgroova-the outer edge of the bottom surface of said glQOl/ being-disposed radially inwardly of the main surface of the piston, said piston havinga'pe'ripheral groove generally below said ring groove `and Acommunicatingwith the interior ofthe piston `at `sub- Steniallyf all pointe.' ,crcumierentallv of the .piston, said peripheral groove being inclined down- .wardly` inwardly of the piston, the inner; edge 1of,said-.peripheral groovewbeing substantially coincident withthe outer edge of thejloottom surface of said ring groove, said. ring having a circumferential groove in itsunder surface, the radiallylinner edge of said circumferential groove vbeingidisposed .radially outward ubeyond the outer .edge. of .theLbDttOm surface of said ringgroove. 8;; Apstonand piston.ring`.construction, comprising, a piston having a ring groove, a ring in said groove, the bottom surface of said groove terminating radially inwardly from the main surface of the piston, said piston having a peripheral groove generally below said ring groove and communicating with the interior of the piston, said ring having a circumferential groove in its under surface, the radially inner edge of said wardly of the outer edge ofthe lower surface circumferential groove being disposed `outwardly -beyond and in a plane belowzthe 'radially outer edge of the bottom surface of said ring groove.

.9. A piston and piston ring construction, comprising, va piston having a ring groove, a, ring in said groove, the bottom surface of'said groove terminating radially inwardly` from the main surface. of the piston, said piston having a peripheral groove generallyl below said ring groove .and communicating with the interior of thepiston, said ring having a circumferential projection on its under surface disposed radially outward beyondthe radially outer Aedge of the bottom sur- -.face of .said ring groove, said `projection extending i below the bottomsurface of said ring groove, said projection having a circumferential groove in its under surface, the `portion of said circumferential groove, as determined by its cross section, deiining the :radially inner termination of the groove, being so shapedthat the projection downwardlyof saidportion isdisposed radiallyloutof vsaidring groove.` i

w): "10. A piston and piston ring constructiomcomprising, apiston having a ring groove, a ring in :said groove, said ring having a portion of its pe- 'ripheral `surface disposed radially inwardly ofthe `outermost 'radial extent of the ring, the bottom surface of said groove terminating'. radially inwardly' from .themain surface of the piston, said piston `havin'glan inclined peripheral groove belowsaid ring-groovelxand communicating with thel interior ofthe piston, ,said `ring having a circumferential groovelin its under surface, the radially. inner edge ofi fsaid circumferential groove -being' disposed outwardly :beyond the, radially outenedge, of theubottom surfaceof saidring groove, and` said circumferential groove being `positioned transversely across the inclined pro- -jection `of said inclined` peripheralgroove.

cylinder 'iwall' .and az cut-away `portion disposed radiallyj inwardly; '.from said first portion, the bottom.;SurfaceoffiSaid 'groove terminating radially inwardlyrfromlthe. main surface `of the piston, saidpistonfhaving av peripheral groove gen,- erally below said ring groove and 'communicate ing with` thelinteriorof the piston, said ringhav- .ingacircumferential groove in its under surface, theradial1yi` inner edge of said `circumferential groove being` Vdisposed outwardlybeyond the radially outer edge of the bottom surface'of said ring groovel p ,J .f1

y .12rApistoni and piston ring construction, comprisng.: a;;pistoni.having a ring groove, a ring in said'. groovasaid ringlhaving a tapered peripheral -surface, ,.thevbottom.surface of said groove termina-ting; radially inwardly from th-e main surifaceiofthepiston;said piston having a periph.- eral groove-.generally below said ring groove and :communicating ,with the interior,l ofthe piston, said; ring having .a circumferential wgroove in its undersurfaceathe.radially inner edge of `said cir-"- cum-ferential groove being dispo-sed outwardly beyond the radially outer edge of th-e bottom surface of said ring groove.

I13. A piston and piston ring construction, comprising a piston having a ring groove, a ring in said groove, said ring having a first portion of its peripheral surface adapted to engage the cylinder wall, and a cut-away portion disposed above and radially inwardly from said first portion, the

bottom surface of said groove terminating radially inwardly from the main-surface of the piston, said piston having a peripheral groove generally below said ring groove and communicating with the interior of the piston, said ring having a circumferential groove inits under surface, the radially inner eidg-e of said circumferential groove being disposed outwardly beyond the radially outer edge lof the bottom surface of s-aid ring groove. v

14. In a construction of the character described, the combination comprising, a piston having .a ring groove, a ring in said groove, the outer edge of the bottom surface of said groove being disposed radially inwardly of the main surface of the piston, said piston having a peripheral groove generally below said ring groove and communicating with Vthe interior of the piston at substantially all points circumferentially of the piston, said ring having a circumferential groove in its under surface and adjacent its outer surface so that the outer edge of said circumferential groove scrapes oil from the cylinder wall as the ring travel-s in one direction relative thereto and changes .the course of the oil bydeflection whereby it discharges into said peripheral groove of said piston, the upper surface of said peripheral groove being located inwardly of the line of deflection of the oil.

15. In a constructionv of the character described, the combination comprising, a piston having a ring groove, a ring in said groove, the outer edge of the bottom surface of said groove being disposed radially inwardly of the m-ain surface of the piston, said piston having a peripheral groove generally below said ring groove and communicating with the interior of the piston at substantially all points circumferentially of the piston, said ring having a circumferential. groove in its under surface, and adjacent its outer surface so that the outer edge of said circumferential groove scrapes oil from the cylinder wall as the ring travels in one direction relative thereto and changes the course of the oil by deflection whereby it discharges into said peripheral groove of said piston, the upper-surface of said peripheral gro-ove being located inwardly of the line of deflection of the oil, and the lower surface of said peripheral groove being located outwardly of said lino of deflection.

16. In a construction of the character described, the combina-tion comprising, a piston having a ring groove, a ring in said groove, the outer edge of the bottom surface of said groove being disposed radially inwardly of the main surface of the piston, said piston having a peripheral groove generally below said ring groove and communicating with the interior of the piston at substantially all points circumferentially of the piston, said ring having a circumferential groove in its under surface, and adjacent its outer surface so that the outer edge of said circumferen- -tial groove scrapes oil from the cylinder wall as :the ring travels inone direction relative thereto :and changes the course of the oil by deflection whereby it discharges at a downward and inward angle into and through said peripheral groove of said piston, the uppei surface of said peripheral stantially all points circumferentially of the pislton, said ring having a circumferential groove in its under surface, and adjacent its outers'urface so that the out-er edge of said circumferential groove scrapes oil from the cylinder wall as the ring travels in one direction relative thereto and changes the course ofthe oil by deflection whereby it discharges at a downward and inward angle into and through said peripheral groove of said piston, the upper Surface of said peripheral gro-ove being inclined downwardly and inwardly yand located inwardly of the line of deflection of the oil, .and the lower surface of said peripheral groove being inclined downwardly and inwardly and located outwardly of said line of deiiection. 18. A piston construction comprising a ypiston having a ring groove, the bottom surface of said groove terminating radi-ally inwardly from the main surface of the piston, said piston having a continuous peripheral groove inclined radially inwardly and communicating with the interior of the piston, and the inclined projection of ksaid inclined periph-eral .groove intersecting the horizontal projection of said ring groove within the cylindrical projection of said main piston surface.

19; A pis-ton and piston ring construction comprising .a piston having a ring groove, a ring element in said groove, said ring element having a circumferential groove in its under surface, said piston having a continuous peripheral gro-ove inclined radially inwardly and communieating with the interior of the piston, and the circumferential groove of said ring element being positioned transversely across the inclined projection of said inclined peripheral groove.

CARL W. HOLLINGSWORTH.

REFERENCES CITED V'The following references are of record in'. the file of this patent:

UNITED STATES PATENTS Sweden Mar. 15, 1934 

